1. Field of the Invention
This invention relates generally to devices for extending the distance of a plank used in a scaffolding system away from a structure. In the trade, such devices are commonly referred to as ladder jacks. More specifically, the present invention is a telescoping ladder jack with adjustable scaffold plank lock.
2. Description of the Related Art
Ladder jacks are used by roofers, siders, painters, and others in a trade that requires work on either the face or roof of a structure. Employed when two or more ladders are utilized against a common face of a structure as in a scaffolding system, one ladder jack is attached to each such ladder, at equal heights. The ladder jack typically attaches to the ladder through the use of a hook mechanism. When so attached to two or more ladders at equal heights, the ladder jacks work to offer extension from the structure, via a rigid member that facilitates support of a scaffold plank.
The prior art discloses several devices that may be used as a ladder jack for the support of scaffold planks. As an example, U.S. Pat. No. 5,020,757 (Sulecki et. al) discloses a ladder jack that is attached on the outside of the employed ladders via a hook, is adjustable for varying inclines, and features a threaded bolt, wing nut, and bracket which serves as a stop for the work platform.
Further, U.S. Pat. No. 6,045,102 (Terenzuni), discloses a multiple use tool that combines a roof hook, a roof bracket, and a ladder jack. The device in the Terenzuni patent, when employed as a ladder jack, is utilized on the outside of the employed ladders, locks into horizontal position via a locking mechanism that allows for adjustment for variations in incline, and also features a device to stop the work platform from sliding off the end of the disclosed tool. The Terenzuni patent employs a set of hooks for attachment to two rungs of the employed ladders.
These ladder jacks provide a basic platform for securing a scaffold plank at an elevation. However, these ladder jacks are utilized on the outside of a ladder, thus limiting the range of the worker, and not providing separation between the structure and the ladder, to facilitate working at the higher elevations where the pitch of the ladder narrows considerably. Further, the prior art does not provide for a ladder jack that can be set at varying lengths, and securely lock a scaffold plank of varying widths.
A further example is offered by U.S. Pat. No. 4,542,874 (Rönning), which discloses a bracket for support of a scaffold plank, which may be inverted to be used on the inside of an inclined ladder. The Rönning bracket utilizes one ladder hook and an adjustable arm to accommodate varying inclines.
Thus, there remains a need in the art for a ladder jack that attaches to the inside of the employed ladders, thereby creating a work platform that is closer in relation to the surface upon which work in being performed, that can accommodate variations in incline of the utilized ladder. Further, there is a need for a ladder jack that can be set at varying distances from the working surface but that provides for a means of securing a scaffold plank of varying widths.